I. Field
The present disclosure relates generally to data communication, and more specifically to rate selection for a communication system.
II. Background
A wireless multiple-access communication system can concurrently communicate with multiple terminals on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. Multiple terminals may simultaneously transmit data on the reverse link and/or receive data on the forward link. This is often achieved by multiplexing the transmissions on each link to be orthogonal to one another in time, frequency and/or code domain.
The terminals may be distributed throughout the system and may experience different channel conditions (e.g., different fading, multipath, and interference effects). Consequently, these terminals may achieve different signal-to-noise-and-interference ratios (SINRs). The SINR of a traffic channel determines its transmission capability, which is typically quantified by a particular data rate that may be reliably transmitted on the traffic channel. If the SINR varies from terminal to terminal, then the supported data rate would also vary from terminal to terminal. Moreover, since the channel conditions typically vary with time, the supported data rates for the terminals would also vary with time.
Rate control is a major challenge in a multiple-access communication system. Rate control entails controlling the data rate of each terminal based on the channel conditions for the terminal. The goal of rate control should be to maximize the overall throughput while meeting certain quality objectives, which may be quantified by a target packet error rate (PER) and/or some other criterion.
There is therefore a need in the art for techniques to effectively perform rate control in a multiple-access communication system.